Our laboratories offer excellent working conditions and are equipped with the-state-of-the art equipment and instrumentation. Here follows more information on the specific instruments used for the various types of analysis and characterization.
A laboratory at the Physics department at NTNU offers laser-induced heating and thermal emission imaging to study mass transport under steep thermal gradients. We are currently imaging liquid alloy flows through solid semiconductor-core fibers.
The laboratory has a CO2 laser source (G48-2-28W, Synrad) which is used to impose a temperature gradient on a microsystem encapsulated by silica. A high-resolution USB CCD camera (DCU224M, ThorLabs) is used for real-time observation of liquid droplet flows through solid, made possible by differences in the emissivity of the liquid and solid. Software packages, including ImageJ, are used to track and analyze particle motion, and the temperature gradient is assessed with emission intensity mapping.
Materials analysis is carried out with NTNU facilities for XRD, XCT and microscopy at NORTEM and NanoLab.
The X-ray physics group is Norway’s leading research unit in X-ray physics and imaging.
Time-resolved computed tomography for flow in porous media
Time-resolved computed tomography (CT) allows studying single- or multiphase flow in porous media. By injecting fluids into a porous sample, while at the same time performing CT measurements, the flow dynamics can be resolved in 3D. To obtain time-resolved 3D images, reconstruction methods requiring few measured projections are required. Here, compressed sensing algorithms are used, which enable tomography with a time resolution as good as 30 seconds. The time-resolved 3D maps can be analyzed to provide a better understanding of multi-phase flow in porous media, which is important, for example, for improving carbon capture and storage (CCS) technology.
Small- and wide-angle X-ray scattering
X-ray scattering can be used to identify e.g. particle sizes, sample compositions and crystal lattice parameters. Our in-house equipment can be used for both small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), allowing structural features of different sizes to be studied. SAXS/WAXS can be done on several sample types, ranging from particles dispersed in solutions, to centimeter-sized bulk samples. By translating the samples in x and y (see Fig. 2), spatially resolved maps can be obtained, and the two-dimensional (2D) detector, facilitates information about the structure orientation to be captured.
Fourier ptychography microscopy
Fourier ptychography microscopy (FPM) is a recent optical microscopy technique for quantitative imaging of samples with a large field of view. The recovered quantitative amplitude and phase maps can be used to study porous media and biological materials. Figure 3 shows the in-house FPM setup. The sample is sequentially illuminated by partially coherent light-emitting diodes (LEDs) in a 2D array, and the transmitted light is focused by an objective lens onto a camera. As each LED illuminates the sample from a unique direction, the recorded transmission images can be numerically combined to give high-resolution quantitative amplitude and phase images. The quantitative phase images are useful for studying weakly absorbing samples, such as biological tissue, or to study fractures in glass surfaces. Figure 4a shows the reconstructed quantitative phase image from a piglet cartilage histology sample. The quantitative phase information can be used to calculate scattering coefficients (Fig. 4b) giving information about the light transport through the sample.
PoreLab has four specialized laboratories at UiO, all of which are equipped with a wide set of state-of-art techniques to study the dynamics and structure of flow in 2D and 3D porous media.
The laboratories have a full range of high-resolution and high-speed imaging techniques, including two ultrafast Photron Ultima (SA5 and APX) cameras with 7000 fps. at a spatial resolution of 1024×1024 pixels and up to 1 million fps. at a reduced resolution.
In 2020, an important part of our activity has been 3D modeling. PoreLab has acquired a Carbide Shapeoko XL CNC milling machine and two Formlabs Form 3 3D printers that are based on a new Low Force Stereolithography (LFS) technology. This technology allows for 3D printing of very fine, high resolution models in a variety of resin types. The acquisition of these state-of-the-art printers gives us a unique opportunity to quickly design and 3D print synthetic porous materials. Apart of the foray into 3D modeling, we have also engaged in improving the imaging equipment in the labs. The latest addition to our wide array of different cameras are two new high-speed cameras, the Photron WX100 mini. These new cameras can take 4 MP images at 1000 fps (FullHD at 2000 fps) and all the way up to 80K fps for lower resolutions.
PoreLab has also a high-resolution FLIR SC300 infrared camera used for real-time measurements of heat dissipation in fractures, hydro-fractures and porous media flows and a wide variety of DSLR cameras and accompanying optics.
Microscale experiments can be imaged via far field microscopy using a Zeiss Stemi 2000-C distortion-free stereomicroscope that couples to our high-speed and high-resolution cameras. This is currently in process of being upgraded for enhanced magnification. Flicker-free illumination sources tailored for the different applications (including high-speed microscopy) are also available. PoreLab have recently bought a Krüss DSA25 drop shape analyzer to perform direct measurements of surface tension, wetting properties and surface free energy, as illustrated in Fig.1.
Additionally, the PoreLab laboratories include a large set of different optical equipment, such as lasers with different intensities and wavelengths, lenses and other optical components, cameras and microscopes for Particle Image Velocimetry. The labs are well equipped to perform homodyne correlation spectroscopy for the measurement of particle velocity fluctuations in fluids, diffusion constants and viscosities. PoreLab developed a 3D optical scanner which makes it possible to measure 3D fluid structures in refraction index matched porous media. This equipment can be used to study dispersion in mono-phase flow and two-phase flow studies.
In addition to this wide variety of state-of-art techniques, our laboratories are also fully equipped with standard fluid mechanics labware, such as capillary viscometers, high-precision scales, pressure and temperature sensors, surface treatment chemicals for the control of wetting properties and general laboratorial glassware. By focusing on both standard and state-of-art techniques in the same physical space, our laboratory benefits from a relatively high degree of independence.
The core analysis laboratory is equipped with state-of-the-art equipment for routine and special core analysis. Included are core preparation equipment (drilling, cutting, cleaning and saturating core plugs), porosimeters, permeameters and apparatus for core plug resistivity measurements. The laboratory has specialized equipment like automated centrifuge for capillary pressure and relative permeability measurements and core flooding rigs for various enhanced oil recovery processes. The main components in the flooding rigs are core holders, pumps, fluid lines, fluid containers, pressure sensors and flow meters.
The laboratory is also equipped with micro-computer tomograph (CT). This micro-CT has a tailor made miniature (5mm diameter) core flooding set up which is used in pore scale studies. In addition the laboratory has microfluidics apparatus where the main components are glass micro models, syringe pumps, microscopes and digital cameras with large monitors.
Supplementary equipment for fluid and fluid/solid interaction analysis includes interfacial tension apparatus (pendant drop and spinning drop), contact angle apparatus, devices for zeta potential and particle size measurements, densitometers, viscosimeters and rheometers.